1. Field of the Invention
The present invention relates to an MPEG decoder for decoding an MPEG stream that is made by compressing and encoding moving pictures according to the MPEG (Moving Picture Experts Group) method, and also relates to an MPEG encoder for generating an MPEG stream by compressing and encoding moving pictures according to the MPEG method.
2. Description of the Related Art
It is necessary to provide an arrangement for parallel processing in order to improve the processing performance of MPEG decoders. In MPEG decoders, however, a processing sequence needs to be maintained due to dependencies between the variable-length decoding process, the peripheral prediction process, the inter-frame prediction process, etc. It is thus believed that parallel processing cannot easily be implemented in a straightforward manner.
There are some arrangements for parallel processing in MPEG decoders such as a parallel processing scheme at the block level (see Patent Document 1) and a parallel processing scheme at the MPEG2 slice level (see Patent Document 2). The parallel processing scheme at the block level processes blocks constituting a macroblock in a parallel manner, and the parallel processing scheme at the slice level processes slices constituting a picture in a parallel fashion.
The MPEG decoder shown in Patent Document 1 performs variable-length decoding in a serial manner with respect to the blocks, which makes it necessary to drive the variable-length decoding unit at high speed. There is thus a problem in that the operating frequency needs to be increased.
The MPEG decoder shown in Patent Document 2 utilizes the fact that an MPEG2 picture is divided into slices. Since slice-based division is not necessarily implemented in MPEG4 or H.264, however, there is a problem in that this MPEG decoder may not be able to be used in many situations.
In MPEG encoders, also, there is a need to provide an arrangement for parallel processing in order to improve processing performance. Since a processing sequence needs to be maintained due to process dependencies, however, it is believed that parallel processing cannot easily be implemented in a straightforward manner.
Accordingly, there is a need for an MPEG decoder and an MPEG encoder that can achieve high processing performance.
[Patent Document 1] Japanese Patent Application Publication No. 10-56641
[Patent Document 2] Japanese Patent Application Publication No. 11-187393
[Patent Document 3] Japanese Patent Application Publication No. 2003-32679